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Kernel Traffic #198 For 30 Dec 2002

By Zack Brown

Table Of Contents

Mailing List Stats For This Week

We looked at 853 posts in 4246K.

There were 267 different contributors. 138 posted more than once. 136 posted last week too.

The top posters of the week were:

1. Complaints About fbdev Design

10 Dec 2002 - 22 Dec 2002 (15 posts) Archive Link: "atyfb in 2.5.51"

Topics: Framebuffer

People: David S. MillerJames SimmonsAlan Cox

In the course of discussion, David S. Miller remarked, "I've always stated that the whole fbdev model was flawed, it makes basic assumptions about how a video card's memory and registers are accessed (ie. the programming model) and many popular cards absolutely do not fit into that model." James Simmons replied, "I agree that the design of the /dev/fbX interface is not the best. Unfortunely we are stuck with it. Changing it would break userland apps." And David replied:

I totally understand. I do not suggest to break fbdev in it's current form, too much stuff uses it.

My main point was, don't be surprised the X servers, like the ATI driver, don't use fbdev and instead just mmap the device and simply program it directly.

fbdev is nice, in the specific cases where the device fits the fbdev model, because once you have the kernel bits you have X support :)

Alan Cox also remarked here, "fbdev also can't be used in some situations on x86. Deeply fascinating things happen on some x86 processors if you execute a loop of code with an instruction that crosses two different memory types."

2. Framebuffer Driver For Intel 810/815

11 Dec 2002 - 20 Dec 2002 (4 posts) Archive Link: "[FBDEV]: Framebuffer driver for Intel 810/815 chipsets"

Topics: Framebuffer, Sound: i810

People: Antonino DaplasJames SimmonsDave Jones

Antonino Daplas said to James Simmons:

It seems the fbdev framework is stable enough, and already in the development tree. So, I'm submitting a driver for the Intel 810/815 for review and perhaps inclusion to your tree (to get more testing), and hopefully merge with Linus's tree.

The patch is against linux-2.5.51, but will not work yet because of 2 reasons:

  1. agpgart is not working for the i810
  2. support for early agp initialization needs to be added.

Once #1 is fixed, the driver should work as a module. And once #2 gets included, the driver can be compiled statically. Dave Jones (thanks for the help, by the way) has already #2 in his tree (tested and works), and is currently working on #1 (I have a hacked version at home).

The driver should be compliant with fbdev-2.5, and should support most if not all features that are to be expected (modularity, state saving and restoring, full hardware support, etc). One thing also that's very important for many people is that the driver will work with XFree86 with its native i810 drivers without further modification, and quite stably too.

The patch is at

James replied, "Applied !!!!"

3. Linux 2.4.21-pre2 Released

18 Dec 2002 - 20 Dec 2002 (9 posts) Archive Link: "Linux 2.4.21-pre2"

People: Marcelo Tosatti

Marcelo Tosatti announced 2.4.21-pre2, and included the ChangeLog.

4. chipsfb.c Updated To New 2.5 Framebuffer API

18 Dec 2002 - 20 Dec 2002 (2 posts) Archive Link: "[PATCH] update chipsfb.c to new API"

Topics: Framebuffer, Ioctls

People: Paul MackerrasJames Simmons

Paul Mackerras said:

Here is a patch which updates chipsfb.c to the new 2.5 framebuffer API. It simplifies the driver quite a bit, partly because the new API is simpler and partly because the driver really can only handle one 65550 chip, since we access the chip via inb/outb to fixed I/O port numbers.

I have tested it on a powerbook 3400, which has a C&T 65550 video chip with 1MB of VRAM, and it seems to work just fine, at least in 8 bit mode. I guess I still need to add the pseudo_palette stuff for 16 bit mode. Unfortunately I can't test it under X at the moment because the X server I have installed on the 3400 is Xpmac, which doesn't work any more because the VC_GETMODE etc. ioctls have been removed. The 3400 is an old and slow machine with a small hard disk and an old Linux/PPC installation on it, and I don't really want to compile up XFree86 on it.

James Simmons replied, "Great!! Applied."

5. Patch Submission Preferences

19 Dec 2002 - 20 Dec 2002 (3 posts) Archive Link: "[PATCH] [v850] Reduce redundancy in v850 linker scripts"

People: Linus TorvaldsMiles Bader

Miles Bader submitted a patch, and Linus Torvalds requested:

Can you please make your patches be rooted the "standard" way, ie do

diff -ruN linux-old-dir linux-new-dir

so that they apply cleanly with a "patch -p1" and the diff headers say something like

        --- xxxx/arch/v850/
        +++ yyyy/arch/v850/

because that's how all my tools are set up to take patches.

I've done it by hand now, but it's somewhat tedious, and if I'm lazy (most of the time) it ends up meaning that I normally just drop patches that don't apply cleanly.

6. Kernel IRC Discussions

26 Dec 2002 (6 posts) Archive Link: "Kernel Chat Room"

People: Tomas SzepeArnaldo Carvalho de MeloRik van RielMarc-Christian Petersen

An anonymous person asked if there were any kernel chat rooms available. Marc-Christian Petersen pointed him to, but the anonymous person said they didn't mean a newbie chat room. Tomas Szepe replied, "You aren't serious, are you? Can you at least go have a look before you frown upon those people in #kernelnewbies?" And Arnaldo Carvalho de Melo also told the person, "that is just the name, go there..." And Rik van Riel also added:

That's exactly the reason we have 'newbies' in the name: to keep the 1337 f01kz out and have a place where we can talk without having 1337 f01kz laugh at you.

People who are interested in learning about kernel hacking, you're always welcome at: / #kernelnewbies







Sharon And Joy

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